This invention relates to a method for preparing 2-oxoalkanoic acids. In particular, this invention relates to a method of preparing 2-oxoalkanoic acids from alpha-nitroketones.
The preparation of oxoalkanoic acids or keto acids has been described by Walters, Chem. Rev. 41, 585-598 (1947). One method for the preparation of the acids involves initially reacting an acyl halide and a metal cyanide to form an acyl cyanide. The acyl cyanide is thereafter hydrolyzed to the keto acid. This procedure, however, is said to be inapplicable for obtaining keto acids having more than five carbon atoms. Another method involves hydrolysis of an oxime ester. In this procedure, to an oxime dissolved in formic acid and maintained at 0.degree. C., is added nitrosyl sulfuric acid. However, it is reported that the conversion from the oxime to keto acid is generally poor and the method is not applicable to the preparation of all keto acids. Yet another method involves refluxing a fatty acid ester, diethyl oxalate, and sodium ethoxide in ether thereby forming an oxaloester. The oxaloester is subsequently treated with boiling dilute sulfuric acid to obtain the keto acid. In those instances where longer chain keto acids were desired, such as those having 10 or more carbons, the method was conducted for a period of 100 hours. One further method involves hydrolysis of the addition product of Grignard reagents and diethyloxamates at very low temperatures. The preparation of diethyloxamates is said to have occurred over a tediously long refluxing time. It is apparent, therefore, that each of the aforementioned methods suffer serious disadvantages including the inability to produce substantial amounts of higher keto acids or the necessity to conduct the process over extended periods of time.
It is therefore an object of this invention to provide a novel method for the preparation of 2-oxoalkanoic acids.
It is another object of this invention to provide a method for the preparation of 2-oxoalkanoic acids in good yields.
Yet another object of this invention is to provide a method for the preparation of 2-oxoalkanoic acids from materials having long storage lives.
Other objects and advantages will become apparent from the following detailed description and examples.